1. Field of the Invention
The present invention generally relates to insulator and metal polishing operations performed in the processing of semiconductor wafers and, more particularly, to a method and apparatus for reconditioning the carrier backing film between polishing operations to maintain the uniformity and planarity of the polish on a wafer-to-wafer basis.
2. Description of the Prior Art
Insulator and metal polish operations performed in the processing of semiconductor wafers are performed on commercially available polishers, such as the Westech 372/372M polishers. These polishers have wafer carriers with an insert, or carrier backing film, which acts as the holding device during transport of the wafer to and from the polishing pad, as well as during the polish cycle. A carrier backing film that is widely used is the Rodel DF-200 product which is of a sponge-like composition. The DF-200 product is a buffed poromeric film having a thickness of about 0.013" to 0.017" that is laminated to mylar for greater dimensional stability. The resulting DF-200 thickness is about 0.024" to 0.028" with a compressibility of about 7 to 23 percent, and is standardized for 2", 3", 3.25", 100 mm, 125 mm, or 150 mm wafers.
The ability to establish and maintain the uniformity and planarity of the polish on a wafer-to-wafer basis is difficult. The degradation of the carrier backing fill--caused in part by the build up of slurry deposits in the film during the polish process--is a major contributor of polishing non-uniformity. Also, the film tends to collapse over time causing polish process results to deviate on a wafer-to-wafer basis. This degradation is time-dependent, yet unpredictable, and nearly always unrecoverable.
In light of the foregoing, there exists a need for a reliable reconditioning device and method of reconditioning the carrier backing film between polishing operations.